It is known to use adjustable clamp assemblies, for example, to couple two objects together through a clamping action. FIG. 1 illustrates an example in which two elongate objects A and B are to be clamped together end to end. The objects may be made of any material that is practical for the purpose for which the clamped objects are used, and in particular may be made of wood, chipboard or the like, or of other materials such as plastics and/or metals including steel or aluminium where suitable.
A known approach for clamping such objects together end to end involves creating cut-out portions in the objects, and using clamps to pull the cut-out portions together. An example of a suitable known cut-out arrangement is shown in FIG. 2.
In FIG. 2, the cut-out arrangement includes cut-away portions A″, B″ made in objects A and B respectively, so that known clamp mechanism 200 can be inserted into the combined cut-away portion A″, B″.
The known clamp mechanism 200 includes a first clamp member 202 that abuts an inner surface 203 of cut-away portion B″, and a second clamp member 204 that abuts a corresponding inner surface of cut-away portion A″. The clamp members 202, 204 are connected by a shaft 206 that passes through respective holes (not shown) in the clamping members 202, 204. The shaft 206 is free to rotate within the holes in the clamping members 202, 204, and is provided with a head portion 208 at one end that abuts an outer surface of the second clamping member 204.
The end of the shaft 206 opposed to the head 208 is provided with a screw thread 210, with which a nut 212 (shown in cross-section) is threadably engaged. The nut 212 abuts an outer surface of the first clamping member 202. Accordingly, by tightening the nut 212, the two clamping members 204, 202 are drawn together, thus drawing the cut-away portions A″, B″together in order to clamp together the objects A, B.
The problem remains, however, that it is difficult in many circumstances to manipulate the known clamp 200 in cut-away portions such as the ones designated as A″, B″ in FIG. 2. In order to tighten the nut 212, it is necessary to use a spanner or other form of lever arm, which requires the spanner or lever arm to be swept through an arc. Thus, when the clamp 200 resides in the cut-away portion A″, B″ it may be difficult to sweep the spanner or lever arm through the arc, because the walls and surface of the objects A, B tend to obstruct the sweep of the arc. At best, it is necessary to manipulate the spanner in very small increments, because the walls of the cut-away portion, B″ limit the sweep of the arc.
Exacerbating the difficulty is the fact that, in use, this form of clamping is often employed on the under surfaces of benches or tables, or within concealed cavities of handrails or sections of other assemblies, where the inaccessibility of the clamp within a confined area may be a problem.
One clamp known in the prior art which attempts to overcome the above disadvantages is described in WO 03/035992. This prior art clamp provides a first bevelled gear member at one end of the clamp mechanism. A special tool is then provided which engages with a pivot locator positioned in a clamp member located adjacent to the end of the clamp mechanism including the first bevelled gear member. The tool includes a second bevelled gear member that engages with the first bevelled gear member, such that the clamp may be operated by a rotation of the tool about its axis, which lies perpendicular to the axis of the clamp mechanism. Accordingly, the clamp may be operated without the necessity to sweep a spanner or lever through an arc that is obstructed by the walls and surfaces of the objects A, B.
However, there remain a number of disadvantages of the clamp disclosed in WO 03/035992. First, the clamp requires a special tool for its operation. This is a particular disadvantage for tradespersons, who are among the main users of these types of clamps, because the clamp tool must be stored, carried and kept on hand along with other tools of the trade. The clamp tool may easily be misplaced, lost, or simply not be within reach at the moment it is required. It is accordingly preferable that the clamp may be operated using a general purpose tool, such as a screwdriver or similar, that the tradesperson will always require and have on hand in the course of work.
Furthermore, applying a tightening torque using the tool, it may easily slip from the pivot locator, which may result in injury to the operator, and/or stripping of the bevelled gears on the clamp mechanism and the tool.
A number of alternative clamp designs are described in the present inventors' prior International Pat. application No. PCT/AU03/01007 that overcome some of the problems known in earlier clamps. Embodiments disclosed therein employ either a cam or worm gear arrangement to provide clamps that may be manipulated using a standard screwdriver or the like rotated about an axis perpendicular to the axis of the clamp mechanism. An embodiment 300 using a worm gear arrangement is shown in FIG. 3.
The adjustable clamp assembly 300 includes first and second clamp members 330, 320 having respective facing inner surfaces 331, 321 adapted to abut against the wall surfaces 203, 205 shown in FIG. 2. The assembly 300 further includes a shaft 340 having a threaded portion 341 at one end.
A sleeve member 356 is provided which has an internal thread, enabling it to be connected to the threaded portion 341 of the shaft 340 by screw-thread engagement. The first clamp member 330 includes holes allowing the rod 340 to pass through.
A worm gear assembly 350 incorporates a worm gear 351 and a worm wheel 352. Accordingly, rotation of the worm gear 351 causes rotation of the sleeve 356, which in turn causes the inner surfaces 321, 331 of the clamp components 320, 330 to be either drawn together or apart along a path of linear motion, depending on the direction of the rotation of the sleeve.
The worm gear 351 is located within a bracket 354 that is integrally formed with the first clamp member 330. The first clamp member 330 thus consists of an integral unit that enables the gear assembly to be entirely contained within one of the cut-away portions, eg A″.
However, the above-described clamping assemblies do not fully satisfy the needs of users of such clamps, and there is therefore an ongoing need for improved means of coupling objects that provide additional advantages, such as enabling further efficiencies to be achieved in installation, and/or that mitigate at least some of the limitations of prior art clamping assemblies.
It is to be noted that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein.